In machining operations, it is often desirable or necessary to set the dimensions of a metal working tool along one or more axes. For example, when using a boring bar to bore a hole, the diameter of the hole depends on the radial distance of the cutting point from the axis of rotation of the bar or workpiece. The depth of the hole depends, at least in part, on the axial position of the cutting tool with respect to the chuck or other machine tool reference element for the bar.
It is further desirable, particularly in production operations, to rapidly and accurately set the tool, such as a boring bar or other cutting tool, to the correct dimensions. This may be done on the machine, as shown in U.S. Pat. No. 3,481,247. It may also be done off the machine. U.S. Pat. Nos. 3,578,868 and 3,597,093 show separate apparatii employing optical systems in which the tool is preset prior to insertion in the machine. After the tool has been preset, it is placed in the machine and the metal working operation performed.
However, optical systems suffer from errors in parallax, ambient lighting problems, and other shortcomings. Other tool setting apparatii use feelers employing mechanical dial indicator gages to set the cutting point, as in U.S. Pat. Nos. 3,504,442 and 3,546,781. More recently, digital transducers and readouts for tool setting gages have become available.
With such presetting gages, a master tool is typically placed in the device and the gage operated to ascertain certain radial and axial reference dimensions from the master, as by a feeler. The master tool is removed and the actual cutting tool inserted in the tool setting gage. The feeler of the gage is then used to adjust the position of the actual tool to the desired dimensions with respect to the references.
However, the construction of the prior art tool setting gages tends to be such as to limit in the size of the tool that can be set in at least on direction. This restricts the use of the gage.
It is therefore, the object of the present invention to provide an improved tool setting gage capable of rapidly and accurately setting a metal working tool over large radial and axial dimensions.
Briefly, the tool setting gage of the present invention includes a base member having a socket for receiving the tool in a generally vertical orientation. A horizontally movable carriage is mounted on the base member for coarse and fine movement toward and away from the tool socket normal to the axis of the tool. The carriage may be moved, in fine adjustment, by a rotatable lead screw. A second, vertically movable carriage is mounted on the horizontal carriage for coarse and fine up and down movement parallel to the axis of the tool.
A feeler is mounted on the second carriage for contacting the cutting point of the tool responsive to the horizontal and vertical movements of the carriages. A transducer ascertains the position of the feeler and operates the digital readout for indicating the axial and radial dimensions of the cutting point.